I have to laugh again, seeing that picture.
Sometimes they will get in the pots to get at the little bugs too... the purslane might have lured them there but they may have also gotten some bugs out of the soil.
This year the purslane is growing from the cracks and odd places like in the middle of the lawn. I don't like lawn anyway, so it's good to find the purslane. Although, we haven't been eating much of it this year either, since I don't know if the dogs have been watering it!